Automatic control device for track tamping machines



P 1, 1954 F. PLASSER ETAL 3,146,727

AUTOMATIC CONTROL. DEVICE FOR TRACK TAMPING MACHINES Filed Feb. 2, 1961 2 Sheets-Sheet l l 5- E I INVENTOR.

HM/z. FLkSSER Sept 1964 F. PLASSER ETAL AUTOMATIC CONTROL DEVICE FOR TRACK TAMPING MACHINES 2 Sheets-Sheet 2 Filed Feb. 2. 1961 INVENTORS Q 'T'Rkl/Z BY JOSEF 'WEURER United States Patent 3,146,727 AUTOMATIC CONTROL DEVICE FOR TRACK TAMPING MACHINES Franz Plasser and Josef Theurer, both of Johannesgasse 3, Vienna I., Austria Filed Feb. 2, 1961, Ser. No. 86,703 Claims priority, application, Austria, Feb. 16, 1960, A 1,203/60 3 Claims. (Cl. 104--12) This invention relates to track tamping machines for railroad tracks and the like, and is more particularly concerned with automatic controls for such machines.

In the type of known track tamping machines to which this invention is especially applicable, oscillatory track tamping tools are mounted on a tool carrier which is vertically adjustable on the frame of the machine. During downward movement of the tool carrier, the tamping tools are forced into the loose ballast of the roadbed and tamp the ballast under the crossties, as they are moved toward each other and by their oscillations. The machine is also equipped with a track lifting device, usually hydraulically operated, which lifts the track into a desired position prior to ballast tamping, and holds it in that position while the ballast is tamped under the track and the adjusted position of the track is thereby secured.

It has now been found that the operation of the tamping tools introduces a significant measure of inaccuracy into the operation of the track lifting device. The reference point in relation to which the desired location of a track section is established prior to lifting is of neces sity located on the tamping machine itself and the progress of the track lifting operation is judged by observing the movement of an element moving with the track section, such as a portion of the lifting mechanism, against this reference. Where the lifting device is automatically controlled, the operation of the lifting device is similarly governed by the relative movement of the machine frame and of a member arranged to move with the track section which is being lifted. It is necessary, therefore, to maintain a fixed machine position during the lifting of a track section if a desired or corrected track position is to be reached.

It has been established that the operation of the tamping tools influences the machine position and that operation of the tamping tools introduces an error into the track lifting operation. More specifically, it has been established that the position of the machine relative to a fixed reference point changes when the tamping tools penetrate into the loose ballast of the roadbed under the crossties. The downward pressure exerted by the machine on the tracks on which it is supported is materially reduced when the tamping tools enter the ballast. It also can be observed that the oscillatory movement of the tools is transmitted to the machine frame with greatly reduced amplitude when the tools enter the ballast.

An exact setting of the desired lifting height of the track lifting device relative to the machine frame should thus be postponed until the working faces of the tamping tools are immersed in the ballast and operation of the track lifting device should not start until the tamping tools are in their operative position, that is, when their working faces are embedded in the ballast by the downward movement of the tamping tool carrier.

A very noticeable improvement in the accuracy of track alignment occurs when these rules are followed. This holds true particuliarly for those track tamping machines of otherwise very desirable design in which the tamping tools and the track lifting device are carried on a portion of the machine frame which overhangs the wheels .of the machine in such a manner that the wheels may be supported on a corrected track section while a non-adjusted track section vertically aligned with the overhanging frame portion is worked upon by the track lifting device and the tamping tools.

The invention aims at generally improving the precision of track alignment and adjustment by providing automatic controls for machines of the type described. It is also concerned with reducing the vibrations transmitted by the tamping tools to the machine frame and to the machine elements supported thereon.

The exact nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing in which:

FIG. 1 is a fragmentary side elevational, partly sectional view of a track tamping machine equipped with the automatic control device of the invention;

FIG. 2 diagrammatically illustrates the control device of FIG. 1 and its operation; and

FIG. 3 is a sectional front view of the track lifting device.

Referring to the drawing in detail, and initially to FIG. 1, there is seen the front end 1 of the track tamping machine of a basically known design. The machine is supported on rails or tracks 7 by means of at least two pairs of wheels of which only one front wheel 30 is visible in the drawing. The front end 1 overhangs the front wheels 30.

The front end 1 constitutes a frame about a transversely extending cavity in which two vertical posts 31 are spacedly mounted. A tamping tool carrier 2 is vertically adjustable on the posts. A transverse horizontal drive shaft 3 in the tool carrier 2 carries an eccentric 32 which causes oscillations of two arms 4 when the shaft 3 rotates. The arms 4 are hinged to respective tamping tools 5 and actuate oscillations of the arms in a common vertical plane.

A hydraulic cylinder 6 is mounted on the tool carrier 2 and contains two pistons 33, the piston rods 34 of which axially project from opposite ends of the cylinder 6 and are pivotally secured to respective tools 5. Pressure fluid admitted to the two axial end portions of the cylinder 6 through the conduit 35 moves the pistons 33 towards one another and thus moves the tamping tools 5 against one another.

As shown in FIG. 1, the tamping tool carrier 2 is near its lowest position on the posts 2 and the tools 5 are in their operative position in which the working faces of the tools penetrate into the ballast 36 on which the crossties 8 rest.

The basic features of the apparatus so far described are known and have been disclosed in more detail in US. Patent 2,876,709, for instance. The vibrations of the tools 5 are effective in solidifying the ballast 36 under the crossties 8 and thus to fix the tracks 7 in a previously adjusted position.

The level of the tracks is adjusted by means of jacks of which but one is seen in FIG. 1. It will be understood that the track tamping machine actually is equipped with at least two jacks for simultaneously adjusting the level of both rails of a railroad track. Track lifting devices of many known types are employed to advantage with the present invention and the jack illustrated is merely illustrative of such devices.

The illustrated jack is that shown in our Patent No. 2,847,943 and essentially consists of a cylinder 9 fastened to the front wall of the track tamping machine, a piston 10 axially slidable in the cylinder 9, a piston rod 11 downwardly projecting from the cylinder 9 and a gripping claw 12 mounted on the rod 11. Pressure fluid admitted to the chamber of the cylinder 9 through conduit 12 under the. piston It raises the piston, the piston rod 11 and thereby the claw 12 which lifts the track 7, this n9 constituting means for actuating the track lifting device 9, 10.

As best shown in FIG. 3, piston rod 11 extends outside cylinder 9 and has fixed to its free end a pivot 44 mounting the two jaws of the gripping claw. The outer ends of the jaws are provided with friction linings 38 adapted firmly to grip the head of the rail 7. Fluid pressure cylinder 39 is pivoted to one of the jaws and cooperating piston 40 is pivoted to the other jaw. Fluid pressure fluid, such as hydraulic fluid, is fed to the cylinder 39 through conduit 41 to operate the gripping claw 12.

The control system of the invention includes a cam 13 on the front wall of the tamping tool carrier 2 and a main operating means constituted by cam-operated switch 14 the actuating arm 15 of which projects into the path of the cam 13 which moves up and down with the tamping tool carrier.

The control system of the invention is better seen in the diagrammatic view of FIG. 2. The main switch 14 is a snap action switch is spring-biased toward a normally open position and is seen in FIG. 2 in the closed position assumed when the cam 13 actuates the arm 15. The switch 14 controls the output of a battery 16 with one pole of which it is connected by a conductor 16. Conductors 17 and 18 constituting a first and second circuit branch lead from the switch 14 to respective terminals of two solenoid valves 20 and 21, the other terminals of which are jointly connected to the other pole of the battery 16 by a conductor 19. An auxiliary push button switch 29, which constitutes an additional operating means, is arranged in the conductor 17 and permits the solenoid of the valve 29 to be operated independently of the position of the automatic main switch 14.

The hydraulic circuit of the jack consisting of the cylinder 9, piston 10, piston rod 11 and claw 12 is seen to include a positive displacement pump 23 connected to the cylinder 9 by the pressure conduit 22. A suction line 24 supplies hydraulic fluid from a sump 25 to the pump 23. A by-pass line 26 equipped with a pressure relief valve 27 connects the pressure conduit 22, and thus the output side or" the pump 23, with the sump 25.

The two valves 20 and 21 are serially arranged in the pressure conduit 22. The first valve 20 is a shut-off valve spring-biased toward the closed position and opened only when its solenoid is energized. The second valve 21 in a two-way valve. In the energized position illustrated it connects the valve 20 to the cylinder 9. When its solenoid is deenergized, the valve is shifted by a return spring 37 to a position in which it shuts oif the flow of fluid from the pump 23 to the cylinder 9 and vents the cylinder to the sump 25 by way of the return line 28.

When the tamping tool carrier 2 moves on the posts 31 into a position near or at the lower end of its stroke, the tamping tools are in their operative position and the switch 14 is closed. When the tamping tool carrier moves upward from the position illustrated in FIG. 1, the cam 13 moves out of engagement with the actuating arm 15 of the switch 14 as soon as the working faces of the tools 5 are substantially withdrawn from the ballast 36. Conversely, the switch 14 is being closed during downward movement of the tool carrier 2 when the faces of the tools 5 enter the ballast 36.

Closing of the switch 14 permits the jack cylinder 9 to be supplied with fluid from the pump 23 but actual operation of the jack depends on actuation of the switch 29. Lifting of the track 7 thus cannot be started until the tamping tools 5 are in operative contact with the ballast 36 and a substantially stable state of the machine is reached. The operator may then establish the necessary length of the track lifting stroke of the piston and thereupon admit pressure fluid to the jack by pressing the button of the switch 2h. When the desired lifting height is reached, release of the button of switch 29 L which is biased toward the open position by a spring (not shown) arrests the jack. The track 7 is then held in the raised position by the jack until the upward movement of the tamping tool carrier 2 causes the switch 14 to be opened and the cylinder 9 to be vented to the sump 25 by the valve 21.

It will be understood that the switch 29 may be automatically operated by servo devices responsive to a track level indicator but such servo devices are not part of this invention and will not be discussed in more detail.

The control device of this invention presents lifting of a track as long as the weight of the tamping machine is not partly supported on the tamping tools 5. It also prevents the free vibrations of the tamping tools from being transmitted to other parts of the machine which cooperate with the lifting device while the latter is in operation. When the working faces of the tools 5 are entered in the ballast, their vibrations are damped and partly absorbed by plastic deformation of the ballast.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically disclosed.

We claim:

1. A track lifting machine comprising, in combination:

(a) a support;

(b) a tamping tool carrier vertically movable on said support;

(c) tamping tool means mounted on said carrier for movement therewith towards and away from ballast supporting said track;

(d) hydraulically vertically movable track gripping means mounted on said support for lifting the track off the ballast;

(e) a source of hydraulic fluid under pressure;

(f) a conduit connecting said source to said track gripping means;

(g) electrically actuated valve means interposed in said conduit between said source of pressure fluid and said track gripping means, said valve means being movable between a conduit opening and closing position;

(h) a source of current;

(i) an electric control circuit connecting the valve means with the current source;

(j) a main switch means in said circuit;

(k) cam means arranged on said tamping tool carrier for operating said main switch means when the tamping tool carrier is in the position wherein the tamping tool means is embedded in the ballast; and

(I) an auxiliary switch in said circuit between the main switch means and said valve means, operation of the main and auxiliary switch means into one position moving the valve means into the conduit opening position to permit hydraulic pressure fluid to flow from the hydraulic fluid source to said lifting means, and operation of the auxiliary switch means into another position closing the valve means in said tamping tool carrier position.

2. The track lifting machine of claim 1, wherein said valve means consists of a first and a second valve, a first circuit branch leading from said main switch means to said first valve and a second circuit branch leading from said main switch to said second valve, and said auxiliary switch is connected in said first branch.

3. In a track tamping machine, in combination:

(a) a support;

(b) a tamping tool carrier vertically movable on the support into a low position;

(0) tamping tool means mounted on the carrier for movement therewith towards and away from ballast supporting the track, the tamping tool means being embedded in the ballast in said low position of the tamping tool carrier;

(d) a track lifting device consisting of a vertically movable rail gripping means mounted on the support for lifting the track oil the ballast;

(e) means for vertically moving the track lifting device to lift the track, said moving means including a hydraulic circuit delivering pressure fluid to said device;

and (f) a control system for operating the track-lifting device moving means, the control system including References Cited in the file of this patent UNITED STATES PATENTS a source of electrical current, valve means including 10 2,847,943 Plasser et a1. Aug. 19, 1958 a first and second valve in said hydraulic circuit, an 2,976,816 Plass r t 1, Mar, 28, 1961 electrical circuit connecting the valve means to the 2,990,736 K r h July 4, 1961 electrical current source for actuating the valve 2,996,016 K ll Aug 15, 1961 means, and a main operating switch and an auxiliary switch means in said electrical circuit, the operation 15 FOREIGN PATENTS of the main operating switch being responsive to the 1,221,502 France Ian-11, 1960 position of the tamping tool carrier and so control- 1,014,140 Germany g- 22, 1957 ling the electrical current delivery to the valve means 1,070,661 Germany 10, 1959 

1. A TRACK LIFTING MACHINE COMPRISING, IN COMBINATION: (A) A SUPPORT; (B) A TAMPING TOOL CARRIER VERTICALLY MOVABLE ON SAID SUPPORT; (C) TAMPING TOOL MEANS MOUNTED ON SAID CARRIER FOR MOVEMENT THEREWITH TOWARDS AND AWAY FROM BALLAST SUPPORTING SAID TRACK; (D) HYDRAULICALLY VERTICALLY MOVABLE TRACK GRIPPING MEANS MOUNTED ON SAID SUPPORT FOR LIFTING THE TRACK OFF THE BALLAST; (E) A SOURCE OF HYDRAULIC FLUID UNDER PRESSURE; (F) A CONDUIT CONNECTING SAID SOURCE TO SAID TRACK GRIPPING MEANS; (G) ELECTRICALLY ACTUATED VALVE MEANS INTERPOSED IN SAID CONDUIT BETWEEN SAID SOURCE OF PRESSURE FLUID AND SAID TRACK GRIPPING MEANS, SAID VALVE MEANS BEING MOVABLE BETWEEN A CONDUIT OPENING AND CLOSING POSITION; (H) A SOURCE OF CURRENT; (I) AN ELECTRIC CONTROL CIRCUIT CONNECTING THE VALVE MEANS WITH THE CURRENT SOURCE; (J) A MAIN SWITCH MEANS IN SAID CIRCUIT; (K) CAM MEANS ARRANGED ON SAID TAMPING TOOL CARRIER FOR OPERATING SAID MAIN SWITCH MEANS WHEN THE TAMPING TOOL CARRIER IS IN THE POSITION WHEREIN THE TAMPING TOOL MEANS IS EMBEDDED IN THE BALLAST; AND (L) AN AUXILIARY SWITCH IN SAID CIRCUIT BETWEEN THE MAIN SWITCH MEANS AND SAID VALVE MEANS, OPERATION OF THE MAIN AND AUXILIARY SWITCH MEANS INTO ONE POSITION MOVING THE VALVE MEANS INTO THE CONDUIT OPENING POSITION TO PERMIT HYDRAULIC PRESSURE FLUID TO FLOW FROM THE HYDRAULIC FLUID SOURCE TO SAID LIFTING MEANS, AND OPERATION OF THE AUXILIARY SWITCH MEANS INTO ANOTHER POSITION CLOSING THE VALVE MEANS IN SAID TAMPING TOOL CARRIER POSITION. 